Pro Audio Reference (N)

N

NAB (National Association
of Broadcasters) A professional trade organization for people working
in the radio and television industry.

NACFM (National Association of Church Facility Managers) "A non-profit organization established in 1995 to promote
networking and educational advancement opportunities for Facilities Management Professionals. NACFM provides an informational resource for church and religious facility management professionals by discussion groups, forums, panels, lectures, seminars, or similar programs or activities (such as this web site) designed to fulfill the purposes of the organization." Another great resource for audio contractors, integrators, etc.

NAG (needed acoustic gain) Acoustics. The gain in decibels required by sound reinforcement to achieve an equivalent acoustic level at the farthest listener equal to what the nearest listener would hear without sound reinforcement.

Nagra Recording. Famous Swiss company whose field tape recorders became the standard for all professionals. The name is so associated with portable recorders that today it is becoming a generic label, like Kleenex or band-aid or XLR.

NAMM (National Association of Music Merchants is the original name;
today it is officially the International Music Products Association but they didn't change the acronym) A professional trade organization
for people working in the music business — primarily in retailing and
manufacturing of music making products. [Popular saying is that NAMM means Not Available; Maybe May.]

NAMMYS The
name of the award given yearly by NAMA (Native American Music Awards).

nano-Abbr. n A prefix for one billionth (10-9)

nanosecond Abbr. ns One
billionth (10-9) of a second.

nanotechnology The science and technology
of building electronic circuits and devices from single atoms and molecules.

nanoweber Abbr. nWb A unit of magnetic flux equal to one billionth
(10-9) of a weber.

Napier, John (1550-1617) Scottish mathematician who invented logarithms and introduced the use of the decimal point in writing numbers. [AHD]

Napier's bones Mathematics. A set of graduated rods used to perform multiplication quickly. Lord Napier is credited with creating them to expedite arithmetical calculations. [Kacirk]

NAPRS (Nashville
Association of Professional Recording Services) Established in
1995 to promote Nashville's finest recording studios, services and engineers
worldwide; dissolved in 2009.

NARM (National Association
of Recording Merchandisers) An industry organization made up primarily
of music retailers acting as an advocate body for the common interests
of merchandisers and distributors of music to industry and public policy
makers.

narrow-band filter Term popularized by equalizer pioneer C.P.
Boner to describe his patented (tapped toroidal inductor) passive notch
filters. Boner's filters were very high Q (around 200) and extremely narrow
(5 Hz at the -3 dB points). Boner used 100-150 of these sections in series
to reduce feedback modes. Today's usage extends this terminology to include
all filters narrower than 1/3-octave. This includes parametrics,
notch filter sets, and certain cut-only variable
equalizer designs.

NC (noise criterion) curves A
unit of measurement for the ambient or background noise level of occupied
indoor spaces, i.e., a measure of its noisiness — true story; real
word. The measured noise spectrum (done in octave bands using an SPL meter) is compared against a series of standard noise criteria (NC) curves
to determine the "NC level" of the space. The standard NC curves take into
account the equal loudness contours of Fletcher-Munson to accurately reflect the listening experience. Each NC curve is assigned
a number (in 5 dB increments) corresponding to the octave band SPL measured
over the octave centered at approximately 1500 Hz. A space is then said
to have a background noise level of "NC-20," for instance, which would
be very quiet, comparable to a quality recording studio. Compare with RC
rating.

near-end Telecommunication term referring
to your end; the local room, as opposed to the far-end.

near-end crosstalk Crosstalk that is propagated in a disturbed channel in the direction opposite to the direction of
propagation of the signal in the disturbing channel. The terminals
of the disturbed channel, at which the near-end crosstalk is present, and
the energized terminal of the disturbing channel, are usually near each
other.
[IEEE Std 802.5]

near-field Acoustics. The sound field very close to the sound source, between the source and
the far field. Technically, a distance less than
one wavelength at the frequency of interest.

near-field monitor A loudspeaker used at a distance of 3-4 feet
(1-1½ meters) in recording studios.

NEC (National Electrical Code) The name
for the United States electrical safety standard (NFPA-70).

negative Electronics. An excess of electrons in a conductor
or semiconductor.

negative feedback The act of
comparing a fraction of the output signal to the input signal at the input
to an amplifier in such a way that the amplifier will keep this fraction
of the output signal always exactly the same as the input signal. Negative
feedback is of prime importance in designing with op amps and audio power
amplifiers. As applied to audio amplifiers, negative feedback is first
attributed to Bell Labs scientist Harold S. Black, as described in the Bell
Labs Technical Review, 1934 and his monumental 87 page U.S. patent
2,102,671 filed in 1932.

negative logic An electronic logic system where the voltage representing one, active, or true has a more negative value than the voltage representing zero, inactive, or false. Also known as negative-true logic, it is normally used in electronic and computing data and communications switching systems for noise immunity reasons. [IEEE Std 1451.2]

negative resistor (aka negistor; also negative impedance) Electronics. A resistor having the opposite characteristics of Ohm's
Law, i.e., the current goes down if the voltage goes up and vice versa.
Certain devices and circuits display this trait and are used mainly to
make negative
resistance oscillators.

neigh The long, high-pitched sound made by a horse. To utter the characteristic sound of a horse; whinny. [AHD]

NEMA (National Electrical Manufacturing Association) Founded in 1926 and headquartered in Rosslyn, VA.

neodymium Abbr. Nd Audio Transducers. Popular rare-earth
metal used to make superior magnets for loudspeakers and microphones. Neodymium
iron boron magnets have a more linear frequency response, are more powerful
and smaller, with higher output levels than conventional iron magnets. First used by Electro-Voice in the late '70s.
[No, it was not named after Neil
Diamond.]

nephew nodeNetworks. A node with one port in standby and all other ports (if any) disabled, disconnected, or suspended. The peer uncle node proxies for the nephew node during bus resets. [IEEE Std 1394b]

network Generally used to mean a multi-computer system (as opposed
to a single computer bus-type system) where multiple
access is allowed from more than one computer at a time. Characterized
by full two-way (duplex) communications between
all equipment and computers on the network. See CobraNet for an example.

neume or neum Music. A sign used in the notation of plainsong during the Middle Ages, surviving today in transcriptions of Gregorian chants. [Middle English, series of notes sung on one syllable, from Medieval Latin pneuma, from Greek, breath.] [AHD]

neural spectrogram Hearing. "The idea that the auditory system takes apart the acoustic information in the same way that a spectrogram does. The separation of different frequencies is done by the basilar membrane. Information about the intensity and phase of different frequency components is kept separate in different neural pathways originating at different sites on the membrane. This separation of frequency information is maintained all the way up to the brain. Intensity activity in each neural pathway corresponds to the darkness of the streak on the spectrogram for the corresponding frequency." [Bregman]

neutral Electronics. 1. Having no electrical charge. 2.
Common point of a star-connected generator or transformer winding. [IEEE Std 1020]

Neve 1073 Console Module Designed by Rubert Neve in 1970, this mic-preamp with 3-band EQ set the standard for all mic channels to follow.

Newport Folk FestivalOne of America's oldest and most famous folk music festivals held in Newport, R.I., usually in July.

Newport Jazz Festival Founded in 1954, it was the premier jazz festival in America, held annually in Newport, R.I., usually in August.

newtonAbbr.N. The International
System unit of force. It is equal to the force required to accelerate
a mass of one kilogram one meter per second per second.

Newton, Sir Isaac (1642-1727) English mathematician and scientist who invented differential
calculus and formulated the theory of universal gravitation, a theory about
the nature of light, and three laws of motion. The sight of a falling apple
supposedly inspired his treatise on gravitation, presented in Principia
Mathematica (1687). [AHD]

NEXT (near-end crosstalk) Category
wiring. Interference between signals on twisted pair cable caused by
damage (usually a loosening of the tight twist required for high speed
transmission) occurring close to the connector.

nickelodeon 1. An early movie theater
charging an admission price of five cents. 2. A player piano. 3. A jukebox.
[AHD]

nickers To neigh softly. [AHD] [ As in what a horse does, not underwear.]

NIH (not invented here) Popular abbreviation
found in technology land, used to described a prima donna corporate attitude
that everything they do must be original. Stems from an unhealthy attitude
that the only solution worthy is their solution, thus rejecting ideas and
inventions not theirs. Makes for very unproductive and unhappy engineering
teams.

NIME (New Interfaces for Musical Expression) Music. International organization for the development of new musical interface design.

Nipper The famous "His Master's Voice" RCA dog. A bull terrier and fox terrier
mix born in 1884 and named for his propensity to nip at peoples' legs.

Nixie tubeVacuum Tubes. A numerical read-out cold-cathode tube first developed by
Haydu Brothers Laboratories in 1955, later purchased by Burroughs Corporation who registered the name. The name Nixie was derived by Burroughs from "NIX I", an abbreviation of "Numeric Indicator eXperimental No. 1." Hit the link for photos.

Noalso Noh Theater. The classical drama of Japan, with music and dance performed in a highly stylized manner by elaborately dressed performers on an almost bare stage. [AHD]
Similar but older than Kabuki.

node Acoustics. A point of minimum amplitude in a one-dimensional standing wave field. A nodal line is a line of minimum amplitude in a two-dimensional filed, and a nodal surface is a surface of minimum amplitude in a three-dimensional field. [Morfey]

node Electronic Circuits. A point of
interconnection between two or more components. Physics. A point or region of virtually zero amplitude in a periodic system.

noise General. Sound or a sound that
is loud, unpleasant, unexpected, or undesired. Physics. A disturbance,
especially a random and persistent disturbance, that obscures or reduces
the clarity of a signal. Computer Science. Irrelevant or meaningless
data. From Latin meaning nausea, discomfort and seasickness. [AHD]

noise cancelling headphones Special headphones incorporating
a microphone built into the headset that samples the ambient sound and
adds it back out-of-phase to the headphone signal. This method actively
cancels or nulls out background noise — works best with low frequencies. See Sennheiser NoiseGard® for an interesting demo.

noise cancelling microphone A special dynamic microphone designed
so both sides of the diaphragm are exposed to the sound field. Close direct
sound strikes primarily one side of the diaphragm causing it to move while
sounds from far away tend to be canceled because they strike the diaphragm
from all sides with no net force.

noise color People working in pro audio
know the terms white noise and pink noise, but few recognize
the terms "azure noise" or "red noise," but they are real terms. Noise
that is not white is called colored noise and will have more energy
at some frequencies than others, analogous to colored light. White noise and pink
noise are well defined and known; much less so are the others.
White noise is so named because it is analogous to white light in that
it contains all audible frequencies distributed uniformly throughout the
spectrum. Passing white light through a prism (a form of filtering) breaks
it down into a range of colors. Examination shows that red light is characterized
by the longer wavelengths of light, i.e., the lower frequency region. Similarly,
"pink noise" has higher energy in the low frequencies, hence the somewhat
tongue-in-cheek term.
The Federal Standard 1037C Telecommunications: Glossary of Telecommunication
Terms defines four noise colors (white, pink, blue & black) and
is considered the official source. No official standard could be found
for the others.
The following list of noise colors is loosely based on a rainbow-prism
light analogy, where a prism creates a rainbow effect by separating white
light passed through it into a visible spectrum labeled red, orange, yellow,
green, blue, indigo, and violet from lowest to highest frequencies. Also
shown is the approximate slope of the power density spectrum relative to
white noise used as the reference:

grey noise: A random pink noise within the audible frequency range subjected to inverted A-weighting loudness curve per IEC 61672.
It gives the listener the perception that it is equally loud at all frequencies.

noise dose or noise exposure Limits of noise exposure published by OSHA (US Department of Labor, Occupational Safety and Health Administration). It is a expressed as A-weightedSPL (dBA) term. Here are some common examples:

noise figure The ratio between the Johnson
noise (or thermal noise) of the equivalent input resistance
of a circuit and its measured noise, expressed in decibels.
It is the ratio of the output noise to the input noise, so the answer is
always positive, with a theoretically noise-free device having a noise
figure of 0 dB.

noise gate An expander with a fixed "infinite" downward expansion ratio. Used extensively for
controlling unwanted noise, such as preventing "open" microphones and "hot"
instrument pick-ups from introducing extraneous sounds into the system.
When the incoming audio signal drops below the user set-point (the threshold point)
the expander prevents any further output by reducing the gain to "zero."
The actual gain reduction is typically on the order of -80 dB, thus once
audio falls below the threshold, effectively the output level becomes the
residual noise of the gate. Common terminology refers to the gate "opening"
and "closing." Another popular application uses noise gates to enhance
musical instrument sounds, especially percussion instruments. Judicious
setting of a noise gate's attack (turn-on) and release (turn-off)
times adds "punch," or "tightens" the percussive sound, making it more
pronounced. A noise gate is to an expander as a limiter is to a compressor. See the RaneNotes Dynamics
Processors and Signal Processing Fundamentals.

noise map Serato DJ. The Serato control vinyl and control CDs each contain a proprietary Noise Map Control Tone that allows Scratch Live to track the motion of the record, simulating the same movement with digital audio. The Serato noise map was co-invented in 2002 by Serato cofounders, Steve West and AJ Bertenshaw ("AJ"). An important distinction is that Serato's noise map is not time code, or anything like time code. It is a unique and proprietary method of tracking the control record's motion based on the mathematical concept of a maximum-length pseudo random bit sequence, which
guarantees uniqueness for the shorted possible section. It is a continuously varying signal rather than a sequence of discrete consecutive location labels as is the case with time code schemes. A noise map makes it is more difficult to determine any exact location since a form of fuzzy pattern matching must be used. However, this increased complexity is more than compensated for by the resultant lower latency, the lack of any need to synchronize with lengthy code words within the signal, and better robustness to noise. In AJ's words: "The idea is to get a sequence of bits in which you can find your position uniquely in the shortest number of bits, without having to synchronize. The problem with time code is that you have to know where each code ends and the next begins. With the noise map you don't have the problem because the code is continuous."

noise reduction Abbr. NRRecording. A signal processing function used to reduce the amount of background noise. See expander.

noise reduction coefficient Acoustics. A single-number rating of the sound absorption properties of a material; it is the arithmetic mean of the sound absorption coefficients at 250, 500, 1000, and 2000 Hz, rounded to the nearest multiple of 0.05. [Harris]

noise shaping A technique used in oversampling low-bit converters and other quantizers to shift (shape) the frequency
range of quantizing error (noise and distortion). The output of a quantizer is fed back through a
filter, and summed with its input signal. Dither is sometimes used in the process. Oversampling A/D converters shift much
of it out of the audio range completely. In this case, the in-band noise
is decreased, which allows low-bit converters (such as delta-sigma)
to equal or out-perform high-bit converters (those greater than 16 bits).
When oversampling is not involved, the noise still appears to decrease
by 12 dB or more because it is redistributed into less audible frequency
areas. Further digital processing usually reverses the benefits of this
kind of noise shaping. See the RaneNote Digital
Dharma of Audio A/D Converters.

NOM (number of open mics) An acronym
believed first created in 1967, or 1968, by Bill Snow after he retired
from Bell Labs and went to work at Altec Lansing Research. It's use was
popularized by Dan Dugan,
the father of the automatic
microphone mixer and Altec
Lansing, the manufacturer of his first design. In Dan's original
design, the automatic mic mixer, like human operators, turned the gain
down on unused mic channels and turned the gain up on active channels,
all the while ensuring that the overall level remained roughly constant.
As a rough approximation, each doubling of the number of open mics (NOM)
cuts the gain by 3 dB, i.e., as more mics are opened up the mic mixer reduces
overall gain. If not, as mics open and close, the reverberation and ambient
noise fluctuates unacceptably. NOM attenuation techniques work to provide
the gain, stability, and low noise qualities of a single open mic with
the benefits of multiple mics. [Historical Note: This concept was first
written about by C.P. Boner & R.E. Boner, in their paper "The Gain
of a Sound System" April 1969, reproduced in Sound Reinforcement: An
Anthology (Audio Engineering Society, NY, 1978.]

nominal This word has several definitions but the one of importance
to pro audio is its engineering sense meaning: insignificantly small; trifling: a
nominal amount. It can also mean "according to plan or design." [AHD]

NOMM (number of open mics & mixers) A term created
by Rane Corporation extending the concept of NOM (above) to include multiple
mixers as well as microphones. As used by Rane, it is NOM-like in that
feedback stability is maintained, however, since large systems have mics
across multiple mixers, Rane includes these mixers in the NOMM calculation.
For example, in audio conferencing, when the chairman is speaking and someone
else quickly answers "yes," coughs, or drops a pen, most mic mixers running
in NOM mode are annoying because they reduce the level of the chairman
mic just because someone else made a noise. The Rane NOMM approach avoids
this annoyance by keeping the chairman's mic at the same gain while still
allowing the interruption to be heard, yet at a reduced gain from its full
gated level.

nomogram 1. A graph consisting of three coplanar curves, each graduated for a different variable so that a straight line cutting all three curves intersects the related values of each variable. 2. A chart representing numerical relationships. [AHD]

non-acoustic voice sensor A device that can detect a person's
voice without the person actually speaking out loud. See TERC.

nonlinear Electronics. The amplitude
of the output is not linearly proportional to the input. If a true sine
wave were transmitted through a nonlinear device, its shape would be changed.
[IEEE] Contrast with linear.

nonlinear distortion Introduction
of frequency components not present in the original signal. Contrast with linear
distortion.

nonvolatile Refers to a memory device that does not lose its
data when power is removed from the system.

norator Electronics. A two-terminal circuit element with a voltage-current
(V-I) characteristic curve consisting of all points on the V-I plane (except
zero/zero because that is a nullator). The
device does not define either the voltage or the current. Used to model
complex circuits for analysis. For example the output of an ideal op amp
can be modeled with a norator, i.e., its output voltage and current can
assume any value. Paired with a nullator creates a nullor.

normalize Recording. The process of linearly increasing all digital samples by the same amount so that the largest original sample reaches a given level. This is done in order to create a maximum signal while maintaining the S/N ratio, and with no clipping when the level selected is 0 dBFS. Analogous to an analog audio system's volume control. See: 10 Myths about Normalization for an interesting discussion of this subject.

Norton's
Theorem In simple terms, states that a complex linear circuit (i.e.,
no exponents or roots in its defining equations) can be replaced by a single
current source and a parallel resistor. See All
About Circuit's Norton's Theorem for detailed explanation. [After Edward
L. Norton.]

notch filter A special type of cut-only equalizer used to attenuate (only, no boosting provisions exist)
a narrow band of frequencies. Three controls: frequency, bandwidth and depth, determine the notch. Simplified units provide only a
frequency control, with bandwidth and depth fixed internally. Used most
often in acoustic feedback control to eliminate a small band of frequencies
where the system wants to howl (feedback).

NOTS (NATO off-the-shelf or niche off-the-shelf) Government procurement term. Most
often referencing software but general use is found. Compare with COTS, MOTS and GOTS.

Novachord Musical Instruments. The name for Hammond's first commercially available synthesizer released in 1938. See The Novachord Restoration Project for pictures and text.

noyPsychoacoustics. A subjective unit of noisiness. For example, a sound of 2 noys is twice as noisy as a sound of 1 noy and half as noisy as a sound of 4 noys. [BBC's J.R. comes through again - thanks!]

NRZ (non-return to zero) A system of binary code where one's are usually represented by a positive voltage and zeroes by a negative number, i.e., neither is ever zero volts.

NSCA (National
Systems Contractors Association) "Founded in 1980 as the National
Sound Contractors Association, the NSCA underwent a name change in 1994
to better reflect the diversification found within the hi-tech industry
of electronic systems. Rather than focusing solely on the installation
of audio systems, today's innovative member companies of the NSCA expanded
into other fields, including audio, video, intercom/paging, telecommunications,
security/access control, and many others." [from NSCA
website]

NSSP (National Standards
Systems Network) A Web-based service launched by ANSI,
along with government and industry partners. A full search & sales
service provides for locating and buying virtually any standard. More than
100,000 global standards are available. Over 25 standards groups provide
technical specs for this database, including ISO.
The EIA endorsed the project.

NTMTM Crossover
Filter (Neville Thiele MethodTM Crossover Filter) Trademarked
term for the patented (U.S. Patent 6,854,005) technology developed by Neville Thiele for Whise
Acoustics in Australia. Two choices were offered, a 4th-order with rolloff
slopes of 36 dB/octave and an 8th-order with 52 dB/octave slopes. The published
curves resemble 4th- and 8th-order cascaded elliptic
filters. Rod Elliot of Elliot Sound Products explores the details in his paper: NTM™ Crossovers.

NTSC (National Television Standards Committee) The United States
and Japan standard for color formatting for television transmission developed
in the 1950s. Compare with PAL/SECAM.

null Mathematics. Of or relating to a set having no members or to zero magnitude. Instrumentation. A reading of zero. [AHD]

nullator Electronics. A two-terminal circuit element with a voltage-current
(V-I) characteristic curve consisting of only the origin point on the V-I
plane, i.e., it always has a value of 0-0. Used to model complex circuits
for analysis. For example the input of an ideal op amp can be modeled with
a nullator; it has zero input current and acts like a virtual short between
its inputs, i.e., zero volts between the inputs, thus an input voltage-current
characteristic of 0-0. Paired with a norator creates
a nullor.

null modem cable Special wiring
of an RS-232 cable such that a computer
can talk to another computer without a modem (thus "null" modem). As a
minimum, a null modem cable reverses pins 2 and 3 on a standard RS-232
cable — but other pins may also need changing and shorting together.

nullor Electronics. A four-terminal
circuit element consisting of a norator and a nullator;
together they model an ideal op amp, i.e., one whose input voltage and
current equal zero and whose output voltage and current can be any value.